TM::ResourceAble - Topic Maps, abstract trait for resource-backed Topic Maps


TM documentation Contained in the TM distribution.

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NAME

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TM::ResourceAble - Topic Maps, abstract trait for resource-backed Topic Maps

SYNOPSIS

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   package MyNiftyMap;

     use TM;
     use base qw(TM);
     use Class::Trait ('TM::ResourceAble');

     1;

   my $tm = new MyNiftyMap;
   $tm->url ('http://nirvana/');

   warn $tm->mtime;

   # or at runtime even:

   use TM;
   Class::Trait->apply ('TM', qw(TM::ResourceAble));
   my $tm = new TM;
   warn $tm->mtime;




DESCRIPTION

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This traits adds methods to provide the role resource to a map. That allows a map to be associated with a resource which is addressed by a URL (actually a URI for that matter).

Predefined URIs

The following resources, actually their URIs are predefined:

io:stdin

Symbolizes the UNIX STDIN file descriptor. The resource is all text content coming from this file.

io:stdout

Symbolizes the UNIX STDOUT file descriptor.

null:

Symbolizes a resource which never delivers any content and which can consume any content silently (like /dev/null under UNIX).

Predefined URI Methods

inline

An inlined resource is a resource which contains all content as part of the URI. Currently the TM content is to be written in AsTMa=.

Example:

  inlined:donald (duck)

INTERFACE

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Methods

url

$url = $tm->url

$tm->url ($url)

Once an object of this class is instantiated it keeps the URL of the resource to which it is associated. With this method you can retrieve and set that. No special further action is taken otherwise.

mtime

$time = $tm->mtime

This function returns the UNIX time when the resource has been modified last. 0 is returned if the result cannot be determined. All methods from LWP are supported.

Special resources are treated as follows:

null:

always has mtime 0

io:stdin

always has an mtime 1 second in the future. The idea is that STDIN always has new content.

io:stdout

always has mtime 0. The idea is that STDOUT never changes by itself.

SEE ALSO

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TM

AUTHOR INFORMATION

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Copyright 200[67], Robert Barta <drrho@cpan.org>, All rights reserved.

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. http://www.perl.com/perl/misc/Artistic.html


TM documentation Contained in the TM distribution.
package TM::ResourceAble;

use strict;
use warnings;

use Class::Trait 'base';

our @REQUIRES  = qw(last_mod);

use Data::Dumper;
use Time::HiRes;

sub url {
    my $self = shift;
    my $url  = shift;
    return $url ? $self->{url} = $url : $self->{url};
}

sub mtime {
    my $self = shift;

#warn "xxxx mtime in $self for url $self->{url}";

    my $url = $self->{url} or die "no URL specified for this resource\n";

    if ($url =~ /^file:(.+)/) {
	use File::stat;
	my $stats = stat ($1);
	return 0 unless $stats; # or die "file '$1' is not accessible (or does not exist)";
#warn "file stats ".Dumper $stats;
#warn "will return ".$stats->mtime;
	return $stats->mtime;
    } elsif ($url =~ /^inline:/) {
	return $self->{created}; ## Time::HiRes::time + 1;      # how can I know?
    } elsif ($url eq 'null:') {
	return 0;
    } elsif ($url eq 'io:stdin') {
	return Time::HiRes::time + 1;                           # this always changes, by definition
    } elsif ($url eq 'io:stdout') {
	return 0;
    } else {                                                    # using LWP is a bit heavyweight, but anyways
	use LWP::UserAgent;
	my $ua = LWP::UserAgent->new;
	$ua->agent("TimeTester 1.0");
	
	my $req = HTTP::Request->new(GET => $url);
	my $res = $ua->request($req);
	
	use HTTP::Date;
	return str2time($res->headers->{'last-modified'});
    }
}

our $VERSION = 0.2;
our $REVISION = '$Id: ResourceAble.pm,v 1.3 2007/07/17 16:22:41 rho Exp $';

1;

__END__